radius, or lack of same, at the die lips. Die buyers who plan to use easy-drooling materials should ask proposed manufacturers about angles and surfaces.
What does work for some polyolefins is a fluoroplastic-based processing aid, which lubricates the die lands and discourages the curl-up-and-out phenomenon that leads to die deposits. Another useful remedy is a thin stream of air directed at the lip-resin contact line.
Allan Griff is a veteran extrusion engineer, starting out in tech service for a major resin supplier, and working on his own now for many years, as a consultant, expert witness in law cases, and especially as an educator via webinars and seminars, both public and in-house. One-day extrusion seminars are scheduled this month in the Chicago area near O'Hare on Jan. 26 and in Atlanta near the airport on Jan. 28. Go to this article in PlasticsToday for further information about these in-person sessions. Griff wrote the first practical extrusion book back in the 1960s as well as the Plastics Extrusion Operating Manual , updated almost every year, and available in Spanish and French as well as English. Find out more on his website, www.griffex.com, or email him at firstname.lastname@example.org.